The clues were there all along when we look back.
McVay loves a TE oriented O.
He clearly has had success in developing and scheming TE's in effective passing O's.
Kendricks was cut shortly after McVay's hire. Obviously, McVay wanted a different type of TE and recognized that Kendricks was not gonna be a good fit.
So, it was beyond certain that a TE was gonna be a high pick. Only question was which TE and how high once Njoku was grabbed.
Look, Lamp is a fine player. He might well see multiple Pro Bowls as a OG or C. But Everett is considered a freak and plays a position highly prized by McVay. One that moves the chains, flips the field, and scores TD's. Interior OL players,, important as they are, don't do those things. Competent interior OL players are easier to find than TE playmakers.
Looking back, I think it's easier to follow McVay's thinking.
I trust McVay on this, and all other O matters. At least until or unless he shows that he doesn't deserve it, that is.